Chlorine-free, non-drying isobutene/diene copolymers and process for their preparation

Abstract

Chlorine-free, non-drying copolymer of isobutene with C 4 -C 10 -dienes having isolated or conjugated double bonds and containing at least 60 mol % of terminal double bonds, and a process for their preparation.

We claim: 
     
       1. A chlorine-free, non-drying copolymer of isobutene and a C 4  -C 10  -diene having isolated or conjugated double bonds and containing at least 60 mol % of terminal double bonds and having a molecular weight M n  of from 500 to 5,000 Dalton. 
     
     
       2. A copolymer as claimed in claim 1, which is composed of isobutene and a diene comonomer in a molar isobutene/diene ratio of from 50:1 to 1:1. 
     
     
       3. A process for the preparation of a chlorine-free, non-drying copolymer from one C 4  -C 10  -diene or different C 4  -C 10  -dienes having conjugated or isolated double bonds and isobutene, whose average molecular weight is from 500 to 5,000 Dalton and which contains at least 60 mol % of terminal double bonds, by cationic polymerization, wherein the isobutene is polymerized with the diene in a molar isobutene/diene ratio of from 50:1 to 0.4:1 with the aid of a boron trifluoride/C 1  -C 15  -alcohol complex whose molar boron trifluoride/alcohol ratio is from 0.25 to 0.9, in the presence or absence of hydrogen fluoride at from -60° to 0° C. 
     
     
       4. A process as claimed in claim 3, wherein hydrogen fluoride is added in a molar ratio of from 0.001 to 0.5, based on the boron contained in the polymerization mixture, to the polymerization mixture. 
     
     
       5. A process as claimed in claim 3, wherein a molar isobutene/diene ratio of from 20:1 to 1:1 is established in the polymerization mixture. 
     
     
       6. A process as claimed in claim 3, wherein 1,3-butadiene or isoprene is used as the diene. 
     
     
       7. A process as claimed in claim 3, wherein isobutene- and diene-containing hydrocarbon streams are used in the polymerization. 
     
     
       8. A copolymer as claimed in claim 1, which contains 1,3-butadiene isoprene as the diene comonomer. 
     
     
       9. A copolymer as claimed in claim 1, which is composed of isobutene and a diene comonomer in a molar ratio of isobutene:diene of from 50:1 to 1:1 and which contains 1,3-butadiene or isoprene as the diene comonomer.